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PhysicsModule2
Questions from Module 2 of the physics component
Question | Answer |
---|---|
What is a piezoelectric crystal? | A crystal that converts mechanical energy to electrical energy and vice-versa; used in transducers. |
Define time-gain compensation. | a method of increasing amplification of the signal with depth to compensate for loss caused by attenuation; controls brightness of an image at different distances from the transducer. |
Define dynamic range. | a measure of the span of signal magnitudes that can be represented or processed by the various components of a system |
What is gain? | control of the overall brightness of the entire image |
Define A-mode. | “amplitude mode” simplest, earliest form of ultrasound. Spike height relates to the strength of the reflection. Single line of information, mainly used in research purposes. Measuring dimension of eyes and lens. |
Define B-mode. | “bright mode” used in 2D real-time/grayscale ultrasound. |
Define M-mode | “motion mode” is used in echocardiography and displays motion of an echo producing structure such as heart valve. 1 dimensional/one line of motion displayed over time. Used only on moving structures. |
What is color doppler? | allows visualization of presence, characteristics, and direction of blood flow. Pulse wave |
What is spectral doppler? | measures blood flow velocity at the Doppler cursor. Allows us to quantify estimates of velocity. Continue or pulse wave |
What is panoramic scanning? | extended field of view. Multiple linear scans placed together to cover large area. |
What is 3D and 4D scanning? | 3D provides images in 3rd dimension (multiplanar) and 4D is 3rd dimension with real-time (w/ movement). |
What is ultrasound contrast? | used in lots of ultrasound modalities as reflectors (such as bubbles) that enhance imaging of blood flow. |
When might a transducer with a small footprint be used? | for skin contact in small spaces (ex. short necks, anterior fontanelle on babies, between ribs) |
What effect does increasing the frequency of the tranducer have on the kinds of scans taken and image obtained? | Higher frequencies yield higher resolution scans but decrease the depth of penetration due to higher attenuation |
Sector (pie-shaped) images are associated with what type of scans? | cardiac |
Linear (rectangular) images are associated with what type of scans? | Aorta, vascular, neck, thyroid, lungs |
Curvilinear (broadened pie) images are associated with what type of scans? | abdominal, OB scan |
Describe the component parts of an ultrasound machine | monitor, keyboard/controls, cpu, tranducer...? |
What is the range equation? | (Velocity of sound in tissue) X (Time between sent and received) divided by 2 |